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Title: Prediction of a high-pressure phase transition and other properties of solid CO/sub 2/ at low temperatures

Abstract

An optimization procedure is used to minimize the Gibbs free energy of solid CO/sub 2/ at pressures 0less than or equal toPless than or equal to16 GPa, with respect to the unit-cell parameters, center-of-mass coordinates, and orientations of all the independent molecules. A lattice-dynamics procedure is used to calculate the libron frequencies. The observed Pa3 structure is predicted at low pressures, and a transition to an orthorhombic Cmca phase is found at P = 4.3 GPa, with a volume change ..delta..V = 0.3 cm/sup 3//mole. The calculated second virial coefficients, sublimation energy, molar volume, pressure-volume relation, and libron frequencies in the Pa3 phase are in good agreement with experiment. In the Cmca phase the calculated libron frequencies agree fairly well with recent Raman scattering results. An analysis of the potential-energy surface shows that the large observed hysteresis associated with the transition may be the result of large barriers between the phases.

Authors:
;
Publication Date:
Research Org.:
Physics Department, Colorado State University, Fort Collins, Colorado 80523
OSTI Identifier:
6844175
Resource Type:
Journal Article
Journal Name:
Phys. Rev. B: Condens. Matter; (United States)
Additional Journal Information:
Journal Volume: 38:9
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CARBON DIOXIDE; CRYSTAL-PHASE TRANSFORMATIONS; CRYSTAL STRUCTURE; FREE ENTHALPY; HYSTERESIS; POTENTIAL ENERGY; PRESSURE DEPENDENCE; SOLIDS; VERY HIGH PRESSURE; CARBON COMPOUNDS; CARBON OXIDES; CHALCOGENIDES; ENERGY; OXIDES; OXYGEN COMPOUNDS; PHASE TRANSFORMATIONS; PHYSICAL PROPERTIES; THERMODYNAMIC PROPERTIES; 360602* - Other Materials- Structure & Phase Studies

Citation Formats

Kuchta, B, and Etters, R D. Prediction of a high-pressure phase transition and other properties of solid CO/sub 2/ at low temperatures. United States: N. p., 1988. Web. doi:10.1103/PhysRevB.38.6265.
Kuchta, B, & Etters, R D. Prediction of a high-pressure phase transition and other properties of solid CO/sub 2/ at low temperatures. United States. https://doi.org/10.1103/PhysRevB.38.6265
Kuchta, B, and Etters, R D. 1988. "Prediction of a high-pressure phase transition and other properties of solid CO/sub 2/ at low temperatures". United States. https://doi.org/10.1103/PhysRevB.38.6265.
@article{osti_6844175,
title = {Prediction of a high-pressure phase transition and other properties of solid CO/sub 2/ at low temperatures},
author = {Kuchta, B and Etters, R D},
abstractNote = {An optimization procedure is used to minimize the Gibbs free energy of solid CO/sub 2/ at pressures 0less than or equal toPless than or equal to16 GPa, with respect to the unit-cell parameters, center-of-mass coordinates, and orientations of all the independent molecules. A lattice-dynamics procedure is used to calculate the libron frequencies. The observed Pa3 structure is predicted at low pressures, and a transition to an orthorhombic Cmca phase is found at P = 4.3 GPa, with a volume change ..delta..V = 0.3 cm/sup 3//mole. The calculated second virial coefficients, sublimation energy, molar volume, pressure-volume relation, and libron frequencies in the Pa3 phase are in good agreement with experiment. In the Cmca phase the calculated libron frequencies agree fairly well with recent Raman scattering results. An analysis of the potential-energy surface shows that the large observed hysteresis associated with the transition may be the result of large barriers between the phases.},
doi = {10.1103/PhysRevB.38.6265},
url = {https://www.osti.gov/biblio/6844175}, journal = {Phys. Rev. B: Condens. Matter; (United States)},
number = ,
volume = 38:9,
place = {United States},
year = {Thu Sep 15 00:00:00 EDT 1988},
month = {Thu Sep 15 00:00:00 EDT 1988}
}